Outline

Introduction

Arteriosclerotic changes can lead to circulatory disturbances in various areas of the human vascular system. In addition to pharmacological therapy and the management of risk factors (e. g. hypertension, diabetes, lipid metabolism disorders, and lifestyle), surgical interventions also play an important role in the treatment of arteriosclerosis. Long-segment arterial occlusions, in particular, can be treated successfully with bypass sur-gery. A number of different materials are available for this type of operation, such as autologous vein or pros-thetic grafts comprised of polytetrafluoroethylene (PTFE) or DacronÂ®. Prosthetic materials are used especially in the treatment of peripheral artery disease, such as in aortoiliac or femoropopliteal bypass surgery. The present report will thus focus on this area in order to examine the effectiveness of different bypass materials.Among the efforts being made to refine the newly introduced DRG system in Germany, analysing the different bypass materials used in vascular surgery is particularly important. Indeed, in its current version the German DRG system does not distinguish between bypass materials in terms of reimbursement rates. Differences in cost structures are thus of especial interest to hospitals in their budget calculations, whereas both private and statutory health insurance funds are primarily interested in long-term results and their costs.

Objectives

The goal of this HTA is to compare the different bypass materials used in vascular surgery in terms of their medical efficiency and cost-effectiveness, as well as with regard to their ethical, social and legal implications. In addition, this report aims to point out the areas in which further medical, epidemiological and health economic research is still needed.

Methods

Relevant publications were identified by means of a structured search of databases accessed through the German Institute of Medical Documentation and Information (DIMDI), as well as by a manual search. The for-mer included the following electronic resources: SOMED (SM78), Cochrane Library - Central (CCTR93), MEDLINE Alert (ME0A), MEDLINE (ME95), CATFILEplus (CATLINE) (CA66), ETHMED (ED93), GeroLit (GE79), HECLINET (HN69), AMED (CB85), CAB Abstracts (CV72), GLOBAL Health (AZ72), IPA (IA70), El-sevier BIOBASE (EB94), BIOSIS Previews (BA93), EMBASE (EM95), EMBASE Alert (EA08), SciSearch (IS90), Cochrane Library - CDSR (CDSR93), NHS-CRD-DARE (CDAR94), NHS-CRD-HTA (INAHTA), and NHS-EED (NHSEED).The present report included German and English literature published between the years 1999 and 2004. A list of the search parameters can be found in the appendix. No limits were placed on the target population, and the methodical quality of the included studies was determined using standardised checklists.

Results

The studies included in this health technology assessment compared the following bypass materials: autologous vein, human umbilical vein (HUV) and synthetic materials such as PTFE or DacronÂ®. Both the systematic reviews and the randomised controlled trials comparing autologous vein grafts to other bypass materials come to the conclusion that autologous vein is superior to all other materials. From a medical viewpoint, there are no clear differences between the various synthetic materials.To date, the subject of bypass materials in vascular surgery has not been addressed comprehensively from an economic point of view. Indeed, we were able to identify only one publication that compared the cost of various bypass materials. The remaining health economic studies did not compare costs, cost effectiveness, or quality of life associated with the use of various bypass materials.

Discussion

When deciding which bypass material to use, vascular surgeons take a number of medical considerations into account, including the bypass area, the availability of autologous vein, the amount of operation time available, and the health status of the patient. The studies included in this health technology assessment demonstrate that autologous vein is usually the preferred material for bypass grafts. In contrast, comparisons of various synthetic materials did not show any specific differences. It remains to be seen whether studies on newly developed synthetic materials will show these to have any particular advantages.The randomised controlled trials included in the present report were limited by a number of methodological weaknesses, such as different methods for determining patency rates, sample size and power problems, the interpretation of non-significant results, and a lack of consideration of additional factors.From an economic point of view, there is still great need for further research, and we have attempted to describe a number of pressing questions for health economic studies in the present report.

1. Introduction

1.1 Health policy background

Peripheral artery disease (PAD) is a major public health issue, with a prevalence rate of 20%, for example, in patients who are 65 years of age. Risk factors for PAD include nicotine abuse, diabetes mellitus, lack of exercise, and increasing age. As the severity of illness increases, patients' quality of life deteriorates and medical costs rise. Because the latter is due, in particular, to the costs of bypass surgery, it is important from an economic point of view to compare the findings of studies that have examined the use of various bypass materials.

Among the efforts being made to refine the newly introduced DRG system in Germany, analysing the various bypass materials used in vascular surgery is particularly important. Indeed, in its current version, the German DRG system does not distinguish between bypass materials in terms of reimbursement rates. Differences in cost structures are thus of especial interest to hospitals in their budget calculations, whereas both private and statutory health insurance funds are primarily interested in long-term results and their costs.

1.2 Scientific background

Arteriosclerotic changes can lead to circulatory disturbances in various areas of the human vascular system. In addition to pharmacological therapy and the management of risk factors (e. g. hypertension, diabetes, lipid metabolism disorders, and lifestyle), surgical interventions also play an important role in the treatment of arteriosclerosis. Long-segment arterial occlusions, in particular, can be treated successfully with bypass surgery. A number of different materials are available for this type of operation, such as autologous vein or prosthetic grafts comprised of polytetrafluoroethylene (PTFE) or DacronÂ®. Prosthetic materials are used especially in the treatment of peripheral artery disease, such as in aortoiliac or femoropopliteal bypass surgery. The present report will thus focus on both types of bypass operation in order to examine the effectiveness of different bypass materials.

2. Objectives

2.1 Medical questions

The goal of this report is to evaluate the efficacy of various bypass materials. In order to do so, we will attempt to address the following questions from a medical standpoint:

Are the studies identified in this report adequate in terms of design, as well as methodological transparency and quality?

How effective are the various bypass materials from a medical point of view?

Is effectiveness of the various materials influenced by the age of patients or by other factors?

In which areas is further medical and epidemiological research necessary due to a lack of data or inconsistent findings?

2.2 Economic questions

Because of increasing budgetary pressures in Germany's system of statutory health insurance funds, it is crucial that policymakers have comprehensive information on the cost-effectiveness of particular medical interventions.

From a health policy point of view, the following questions are of particular importance:

Is the use of synthetic bypass materials (e. g. PTFE, DacronÂ®) a cost-effective alternative to autologous grafts?

Is it possible to choose bypass materials based on health economic criteria?

Are the studies identified in this report rigorous in terms of methodological transparency and quality, as required by established health economic guidelines?

Can currently available information on cost-effectiveness be used to make health policy decisions?

In which areas does further health economic research need to be conducted?

The present report included German and English literature published between the years 1999 and 2004. A list of the search parameters can be found in the appendix. No limits were placed on the target population, and the methodical quality of the included studies was determined using standardized checklists.

3.2 Results

We were able to identify 2941 publications related to different materials in bypass surgery. Excluding non-systematic and non-randomised studies left us with 410 publications for further analysis. Of these, we found 13 studies to be relevant to our particular topic and of sufficient methodological quality, including two systematic reviews and eleven randomised controlled trials.

The 13 studies included in our final analysis compared the following bypass materials: autologous vein, human umbilical vein (HUV) and synthetic materials such as PTFE or DacronÂ®. Both the systematic reviews and the randomised controlled trials comparing autologous vein grafts to other bypass materials came to the conclusion that autologous vein is superior to all other materials. From a medical viewpoint, there were no clear differences between the various synthetic materials.

3.3 Discussion

The randomised controlled trials included in the present report were limited by a number of methodological weaknesses, such as different methods for determining patency rates, sample size and power problems, the interpretation of non-significant results, and a lack of consideration of additional factors.

The search parameters were based on terms related to bypass materials. The present report included German and English literature published between the years 1999 and 2004. No limits were placed on the target population.

The methodological quality of the included studies was determined using standardized checklists developed by the German Scientific Working Group "Technology Assessment for Health Care" to evaluate the quality of health economic analyses.

4.2 Results

We identified 1605 relevant publications and selected 220 of them for further analysis. To date, the subject of bypass materials in vascular surgery has not been addressed comprehensively from an economic point of view. Indeed, we were able to identify only one publication that compared the cost of various bypass materials. The remaining health economic studies did not compare costs, cost effectiveness, or quality of life associated with the use of various bypass materials.

4.3 Discussion

From an economic point of view, there is still great need for further research, and we have attempted to describe a number of pressing questions for health economic studies in the present report.

Because of an unimportant number of health economic studies dealing with bypass materials in vascular surgery modeling and realizing such studies would be desirable.

5. Ethical, social, and legal considerations

We were unable to identify any relevant publications dealing with ethical, social or legal aspects related to the use of different bypass materials.

6. Summary of results and discussion

A variety of bypass materials are used in vascular surgery, including autologous vein, HUV and synthetic materials such as PTFE or DacronÂ®. Autologous vein, however, is superior to all other materials. From a medical viewpoint, there are no clear differences between the various synthetic materials.

To date, the subject of bypass materials in vascular surgery has not been addressed comprehensively from an economic point of view. As a result, it is impossible to draw any conclusions here about the cost-effectiveness of various bypass materials. By highlighting the areas in which data on this topic are inconsistent or lacking, we hope to have helped point the way for further health economic studies.

We did not find any relevant publications dealing with the ethical, social, or legal aspects related to the choice of bypass materials, and were therefore unable to conduct a structured evaluation of these issues.

7. Conclusion

When deciding which bypass material to use, vascular surgeons take a number of medical considerations into account, including the bypass area, the availability of autologous vein, the amount of operation time available, and the health status of the patient. The studies included in this health technology assessment demonstrate that autologous vein is usually the preferred material for bypass grafts. In contrast, comparisons of various synthetic materials did not show any specific differences. It remains to be seen if studies on newly developed synthetic materials will show these to have any particular advantages.

The randomised controlled trials included in the present report were limited by a number of methodological weaknesses, such as different methods for determining patency rates, sample size and power problems, the interpretation of non-significant results, and a lack of consideration of additional factors.

From a health economic point of view, additional studies comparing various bypass materials in vascular surgery are needed to provide reliable information on the cost-effectiveness of these materials.